In the reaction,$C_2H_5OC_2H_5 + CO \xrightarrow[150^{\circ}C, 500 \text{ atm pressure}]{BF_3} X$. What is $X$?

$1-$Phenoxypropane is treated with excess of conc. $HI$ at $0\,^{\circ}C$ and the mixture of products is treated with thionyl chloride. The products formed are

An organic compound $'A'$ $(C_9H_{10}O)$ when treated with conc. $HI$ undergoes cleavage to yield compounds $'B'$ and $'C'$. $'B'$ gives a yellow precipitate with $AgNO_3$ whereas $'C'$ tautomerizes to $'D'$. $'D'$ gives a positive iodoform test. $'A'$ could be :

Why is the $C-O-H$ bond angle in alcohol slightly less than the tetrahedral angle,whereas the $C-O-C$ bond angle in ether is slightly greater?

Identify the products $Y$ and $Z$ in the following reaction:
$C_6H_5-O-CH_2CH_3 \xrightarrow[\Delta]{HI} Y + Z$

Find the major product in the given reaction: